Data sending failed

After sending without any problem, this last week we are having problems …: when we are on the last page (send) we click on the black arrow and the screen collapses and remains blocked with a blue background and a white arrow. The screen is frozen and the shipment does not go through. I think it is not a server problem because the files do not arrive there.
Could it be due to some recent update? Do mobile phones have to be updated?
It would help a lot to know if when you press send from the mobile, it will confirm that you have sent the shipment, because sometimes you doubt whether you have sent it or not. Is this possible?

Best regards

In the folder of the mobile application called cybertracker there is a folder “outgoing” which must be empty if the information has already been sent correctly.